Impeller change

captainlarry84

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Freeport NY
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KristenFormer Charter Captain
As part of my spring launch I changed the impeller on my 370 Yanmar. Last time I lube it with soap and just pulled it out and slapped in another. The pump currently has 1566 hours on the unit. Based on the time I removed the pump for a more detailed inspection.
In addition the rear wear plate being grooved the cam was worn. It was worn on the leading edge which caused the cam to pull away from the housing. This wear caused a very sharp edge on the cam which most likely would have torn the new impeller easily.
Changing impellers offshore is not easy task. So if anyone has not removed there pump for a more detail inspection it may be worth it.
 

captainlarry84

Rear Admiral
Joined
Sep 13, 2011
Posts
1,295
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239
Location
Freeport NY
Boat Make
KristenFormer Charter Captain
The Raw Pump... Your must important Maintainance Item!

They are different to some degree. Impeller maintenance on the 315 like the 370 Yanmar is a bear of a job. I think that they designed the raw pump they built the motor around it! A very hard pump to work on. The impellers in these new motors work much harder that years ago. Because the motors are lighter,, smaller putting out more HP, and rev higher they generator a lot more heat so the pumps are doing double duty.
I your pumps as 1200 Hours or more a full inspection is needed. Not only for Yanmars but for any of the newer diesel.
Also be selective in your impeller & always use OEM parts. If you keep a new spare on your boat. Keep it as the spare. Always buy a nice fresh unit off the shelf that has been waiting to be installed in a nice friendly environment, unlike the one on a boat. Also when a pump is removed and reinstalled they can some times become air bound. Put plenty of lube on the blades for the start up and have an assistant looking over the transom for flow. A lot of damage can occur quickly on a new install. Sometimes it is necessary to remove a raw water hose to get things going.
When I look at my water flow at 3000 RPMs….. I am amazed at the volume and pressure shooting out! Which brings me to one more item. Do to this pressure and force your zinc pencils also get hammer. So every 80 hours max they should checked.
 
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